1. In a medium, saute onion and green pepper in vegetable oil until tender.2. Add coconut and curry powder and cook until curry darkens, about 1 minute.3. Stir in cucumber, salt and water.4. Bring to the boil, simmer ten minutes.5. Chill, and then stir in buttermilk.6. Just before serving, coat a small saute pan with cooking spray and saute mustard seeds (if using), cover until they pop.7. Ladle soup into bowls and top with mustard seeds.